1. Field of the Invention
This invention relates to a resin fan shroud for surrounding a cooling fan and guiding cooling air to a radiator in an engine cooling apparatus, and particularly to an improvement structure for integrally forming a reserve tank for storing engine coolant with a resin fan shroud.
2. Related Arts
In the past, in Japanese Unexamined Utility Model Publication No. H.1-174518, Japanese Unexamined Utility Model Publication No. S.55-76824, engine cooling apparatuses wherein a reserve tank for storing engine coolant is formed integrally with a resin fan shroud attached to a radiator for engine cooling have been proposed.
By forming the reserve tank integrally with the fan shroud, the reserve tank installation space can be reduced, reserve tank mounting work becomes efficient, and a coolant flow connection hose between the radiator and the reserve tank can be shortened.
However, neither of the above-mentioned prior art examples considers the actual molding method of the resin fan shroud, and their practical application is difficult. Generally, because the fan shroud is a complicated thin plate shape not having a hollow shape, it is formed by an injection molding method. However, in the former example, it is mentioned that the hollow shape of the reserve tank is formed by a blow molding method (a hollow blow-in molding method). That is, the whole of the fan shroud is molded by the blow molding method. In this case, the molding precision of the fan shroud falls greatly compared to the molding precision by the injection molding method, so that practical application becomes difficult.
In the latter example, it is only mentioned that the reserve tank is molded integrally with the fan shroud, and there is no reference to a specific molding method. However, because the reserve tank is of a hollow shape it is necessary for the whole of the fan shroud to be molded by the blow molding method is the same as the former and, again, practical application is difficult.
It is conceivable to, because of this, after a reserve tank body has been injection molded as a separate part from the fan shroud, join an open end of the reserve tank body to a plate-shaped part of the fan shroud by thermal fusion joining or the like and close the open end of the reserve tank body with the plate-shaped part of the fan shroud and thereby form a tank shape.
However, with this measure, after the fan shroud and the reserve tank body are separately molded, it is necessary to set up a joining step of joining these two, and this leads to an increase in the number of manufacturing steps. In addition, a coolant leak inspection of the joint part between the fan shroud and the reserve tank body also becomes necessary, and this leads to a rise in manufacturing cost. Also, with respect to extreme conditions of use in a vehicle or the like, it is difficult to secure adequate reliability in relation to coolant leakage prevention from the joint part of the reserve tank proper.